Great post! There are so many icon makers and faces out there, it's really just a matter of having the resources to find them, so this should be great for new RPers and those that have trouble finding faces/good icons of faces. wikicon has to be one of my favourite things, personally, and I regularly check pb_updates just to browse, even if I'm not looking for a character. I often end up finding that if there was a face I liked that stuck and someone comes to me saying they had trouble finding a PB I can recall it pretty quickly, like "Oh! Oh I know embargo posted a wide-eyed, dark-haired girl a little ago."
I agree with the above that the no-no's can vary from situation to situation. Most notably, with point number four, sometimes I see a set of icons that I've come across totally unintentionally (in the most recent case, Logan Lerman in 3:10 to Yuma at oldwest) that just makes me go "CHARACTER WITH THAT FACE" and you have a personality for them within seconds of seeing it. Of course, I didn't watch the movie until after I'd started him in a little PSL so there was no attempt to modify him to suit the actor or character of the film. I'm sure instances like this aren't what you're referring to, but rather the "Oh look, [my favourite actor] is skydiving in these icons so I'm going to make my character love skydiving for no other particular reason."